b-Catenin
B -Catenin is closely
associated with carcinoma invasion/metastasis and poor survival. Recent studies
have demonstrated that abnormal expression of B -catenin, especially its
nuclear accumulation, also plays an important role in wingless/Wnt signaling
pathway. In this study, we evaluated immunohistochemically the nuclear
localization of B -catenin in a total of 93 human-endocrine-related tumors
including 1 medullary carcinoma (thyroid gland), 12 parathyroid tumors, 22
carcinoid tumors (digestive tract and liver), 7 islet cell tumors, 26
adrenocortical tumors, 13 neuroblastoma (adrenal gland), and 12 pheochromocytoma
(adrenal gland), and also studied genetic alterations of the B -catenin gene.
Nuclear accumulation of B -catenin was frequently detected in 8 of 22 (36%)
carcinoid tumors and 2 of 7 (29%) islet cell tumors. No genetic alteration in
exon 3 of the B -catenin gene encoding serine/threonine rich domain, which was
phosphorylated by GSK-3 B, was detected in any groups of the endocrine tumors.
However, nuclear accumulation of B -catenin in carcinoid tumors was
significantly correlated with the proliferative marker Ki-67 (MIB-1) labeling
index (p <0.001). Our findings suggest that nuclear transfer and
accumulation of the B -catenin may contribute in the tumorigenesis of carcinoid
tumor as an oncoprotein.
PMID: 12114696 [PubMed - as supplied by publisher]